Impeller for centrifugal pulverizer



Dec. 22, 1964 o. DANYLUKE IMPELLER FOR CENTRIFUGAL PULVERIZER Filed May '7, 1963 INVENTOR. 051% Jazzy/11170, BY

- ATTOIYIVEYJ.

United States Patent Ofifice 3,162,386 Patented Dec. 22, 1964 3,162,386 HVIPELLER FUR CENTRIFUGAL PULVERKZER Ostap Danyluke, Newtown Square, Pa, assignor to Bath Iron Works Corporation, Bath, Maine, a corporation of Maine Filed May 7, 1963, Ser. No. 278,530 12 Claims. (Cl. 241-275) This invention relates to a centrifugal pulverizer, and more specifically to an impeller for projecting outwardly the material fed thereto.

In the type of centrifugal pulverizer referred to, there is generally an impeller which rotates about a vertical axis, supported and driven at the bottom end and fed at the top end through a circular vertical feed tube at the center. The material being crushed enters at the center of the impeller and, by means of vanes, is propelled outwardly under the action of centrifugal force and is discharged, at a relatively high velocity, against either a bed of material or breaker plates. As the crushable material flows outwardly from the center and enters the area of the vanes and then flows over the vanes of the impeller, abrasion of the vanes and the impeller discs occurs and has been a major problem. Impellers have been used which employ renewable shoes on the impeller vanesthat can be readily replaced. However, the abrasive nature of the material being fed dictates the life of these shoes which, in many cases, can be a matter of a few hours. Other impellers have been used which incorporate vanes that are shaped to retain a bed of material to reduce the wear on the vanes. However, the impeller discs are still subject to the abrasive wear of the material being fed.

It is the principal object of this invention to provide an, impeller that will greatly minimize abrasive wear on the vanes and also on the impeller discs.

It is another object to provide an impeller that can be readily and simply manufactured.

Another object is to provide an impeller that can be manufactured from relatively inexpensive materials.

The foregoing objects are achieved, in accordance with my present invention, by providing an improved form of impeller vane so designed that the particles of projected material are guided or channelled through the impeller between the impeller discs with very substantially lessened contact with the surfaces of the discs and the surfaces of 'the vanes. Thus, the life of the impeller discs and of the n of FIG. 1; and

- FIG. 4 is a perspective view of one of the vanes.

In describing a preferred embodiment of the invention illustrated in the drawing, specific terminology has been resorted to for the sake of clarity. However, it is not my intention to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technicalcquivalents which operate in a similar manner to accomplish a similar purpose.

Referring now to the drawing, the impeller comprises an assembly of parts including the upper and lower annular discs 12 and 14 which may be. secured, as by the bolts 15, to a hub 16 which is supported on, and

keyed or otherwise secured to, the rotatable shaft 17.

Shaft 17 is adapted to be driven at'high speed (for example, of the order of from 1800 to 3600 r.p.m.) by drive means, not shown.

Supported above a central circular opening in the annular upper disc 12 is a stationary feed tube 18 through which the particles of material to be reduced in size are fed to the impeller. These particles drop into a cup 19 set in the rotatable hub 16, and when the cup is rotated at high speed, particles of the material quickly fill up the corner areas, as indicated in the drawing, forming an inclined surface for the particles of material which follow. All particles are thereafter ejected from the cup 19 into the region between the upper and lower discs 12, 14, of the impeller and are thrown radially outwardly by the impeller vanes and by the centrifugal forces resulting from the high speed rotation of the impeller.

When conventional types of impeller vanes are employed, the particles of material which are thrown I through the impeller by the vanes tend to spread out into a cone-shaped pattern which originates at the hub of the impeller and spreads toward the outer periphery. The particles thus come into high-speed contact with the undersurface of the upper disc and with the floor of the lower disc and, as a result, these surfaces are subjected to undesirably rapid wear.

In accordance with my present invention, the undesirable rapid wearing of the surfaces of the impeller discs is avoided by so designing the impeller vanes that the particles are confined to a region between the upper and lower discs and are for the most part prevented from coming into contact with the disc surfaces.

The impeller vanes are designed to refocus, so 1 to speak, the impelled particles, thereby to keep to a smaller dimension the large diameter of the cone-shaped pattern. A preferred form of vane is shown in perspective in FIG. 4 and in cross section in FIG. 1.

As seen in FIG. 4, the vane 20 comprises a main radial portion 21 having bosses 22 and 23 for receiving, for example, the bolts 24 and 15 which may be used to secure the vanes to the upper and lower discs 12, 14 of the impeller assembly, as shown in FIG. 1. The vane 20 is equipped with a plurality of spaced-apart circumferentially-extending arms, three arms 25, 26, and 27 being shown in the preferred embodiment. Each of the arms 25, 26, and 2'7 is located respectively at an increased distance from the inner periphery of the annular discs 12, 14, and each is curved or shaped inwardly to form what may be termed pockets, as best seen in FIG. 1. Each of the arms 25, 26, and 27 extends generally circumferentially in the direction of rotation of the impeller, this direction being indicated in FIG. 1 by the arrow 30.

Each of the arms 25, 26, and 27 has a height equal to the spacing between the upper and lower discs 12 and 14 of the impeller assembly, but at their outer extremity, each of the arms is cut back or notchedin the center region. In the illustrated embodiment, the notches 2511, 2671, and 27n are shown as being generally C-shaped, as defined by the upper and lower triangular or fillet-shaped edges.

In addition to the'arms 25, 26, and 27 which extend generally circumferentially in the direction of rotation, as just described, each vane 20 is also provided with a fourth arm 23 which extends in a general direction Op osed to the direct-ion of rotation'of the impeller assembly, and is located generally opposite to the first arm 25. Arm 28 is disposed diagonally inwardly fromthe radial portion 21, as best seen in FIG. 1,- and, likewarms 25, 26, and 27,, is provided with fillet outer edges forming a C-shaped notch 28m. 7

In operation, as the impellervassembly rotates at high speed in the directionof the arrow 30 of FIG. 1, the particles of material fed through tube 18, fall into cup 19, climb up the slope of the bedded material shown e and enters the'regio n of the vanes. 'The innermostpocket toward arm 28, i.e., the rear of the pocket, "from which it enters the following Vane, The 'sloping fillet-shaped tect the vane.

. c impeller discs, The'pocke V ,"pocketare spaced proportionately and are placed-cl6se nermost pockets filling up first, and the other pockets shortly thereafter. Thereafter, most of the particles ejected from the cup 19 are channelled through the G-shaped notches 25h, 26m, and 2711, alonga path indicated in FIG. 1 by the arrows 32. I FIG. 3 is a View, in section, along the line III I II of 'FIG. '1 and depicts the way in which the pockets become lined with lodged particles. These lodged particles protect the arms 25, 26, and 27 and prevent wea-r thereof. Particles which strike the particles already lodgedir the pockets are thrown back into the channel and are then carried through the notch of that particular arm, and: also through the next outer notch or notches. If they should strike the next outer pocket, they would again be thrown back into the channelled strearn.

It will be seen that the arms 25, 26, and 27'function,

s'oto speak, to refocus the particle spread, in that particles which-tend to diverge too widely, either upwardly or downwardly,; from the channelled path defined 'by the It will be understood that the optimum number of subsequent pockets is determined principally by the diameter of the impeller, and that any multiple can be used to efifect the same action.

While the shape of vane may depart from the particular and presently preferred design, which is illustrated in the drawing, I have found the illustrated design to be very satisfactory. In a typical case, the inner. portions of arms 25, 26, and 27 extend out from the radialportion 21 at an angleof'about 40.,'as indicated in FIG. 1, while the extreme fillet shaped endportions .of the arms are disposed at an angle of about 90 relative to the innerportions.

, The new vanes are ofprincipal advantage in centrifugal impellers rused fior reducing abrasive materials, such as silicon carbide, which, in the absence of the vanes of the present invention, cause'rapid and excessive wear of the impellerdiscsa The vanes are made ordinarily of notches 25n,.26n, and 271i, are caused to return to the region of the channel, which is between, but not in con- I tact with either of, the upper and 'lower discs 12,; 14.

Thus, the undersurface of upper disc 12 and the floor of lower disc 14 is protected frdnithe abrasive action'of the otherwisewidely divergent particles, and thus the amount o'f'wear onthe discs 12 and 14 is substantially reduced. I

The function or the fourth arm 28, which extends insteel and can be manufactured as castings with a minimum amount of finishing, or they can be fabricated from formed plates and shapes; The ends of the pockets incorporating the extended fillet shapes can, if. desired, be made'as renewable pieces and fastened to the main body ofthe impeller vanes. Other variations may be included without departing from the scope and spirit of this inventionas defined in the claims. Having describedmy invention, I claim: r 1. 'In' a centrifugal pulverizer for reducing the size of (particles of material, an impeller assembly adapted to be wardly, and 'rearwardly with respect to the direction of impeller rotation, is to direct particles which arev ejected centrifugal 'pulverizer, the: greatest -amountl of abrasive wear occurs where. there is a; sudden change of direction of the material being fed, and where the flow of material 'is in intimate contact witheither the impellerhub, discs,

V rotated at'high speed,'said impeller assembly "including an upper and a lower-horizontally-disposed impeller disc,

and a plurality of radially disposed impeller vanes vertically secured between said discs; eachof said impeller vanes having a radial main portion and having a plurality of cupped arms extending generally circumferentially therefrom in the direction of rotation of said impeller assembly andloctaed at different radial distances from the axisof rotation, said'cupped arms being cupped inwardor vanes. To reduce this wear, rny improv'eddesi i1 emj ploys a bed of material at thegvariou's points gust de-' scribed to protect the impeller components. This v.is a'c complished first by the use of the hollowcup19 at the center of the impeller where the material is fed into the impeller. The sloping'bed of material in the'cup 19 protects thecup and also imparts circular motion to the ma "ter'ial being fed so that it emerges by centrifugal'force in the vane defined by arms 25and 28 is so sh pedfan'd so located that it retains a bed of material iira way to protect the vane, whether the outwardly propelled rnate- V r g i' Apparat'us as claimed: in claim ,4. characterized in I 1y forming pockets, the extremity of'each of said arms having a relatively large lateral notch disposed between the upper. and lower discs for passage'therethrough of particlesof material.

2. App'aratus asclairned in claim 1 characterized in that'theextremities' of said arms have fillet-shaped upper 45 and. lower edges forming generally C-s'haped notches. I that each, vane, is providedwith at least two arms.

43. Apparatus as claimed in claim 2 characterized in 4. 'Appar'atus. as claimedin claim .3 characterized in (that the extremity portion of said arms isZdisPosedat any angle of about relative to theinward portion of said arms. 3'

that the inward portion of said arms is disposed at an an- -ria1 flows toward arm 25, -i. e., thefront of the pocket, or. r

top andbottomlprojections on" the pocket ends retain a fillet-shaped'bed of material wh away from the upper" and j erimpeller discs toward the center of the fspacebetween'the discs: The depth of' thepocketismade' great enough to retain-the maximumsharp edges rather than beveled effectivelytrap' and reta adially; speaking, to prevent ex-' directs the fed material expected size of parti cle fed. to theimpeller, Theiendjf edges of thepockets faciilgthe fiowf'i'of material should be ead vertically toward th g hich follow the innermost gle of about 40 relative ito the 'rad-ial portion of 'said vanes. Y

.fimApparatusa claimed in claim 5 characterized in-that said vane/is provided with an additional armwhich is "located generally opposite to'the innerrnost of said firstdthe 5 .ticles fedto said impeller. assemblyf vizer, s aid V 7 h tion' having extending laterally therefromlat spaced-apart locations atileast-two cuppedharms; the'out'wardextrem- I mentioned arms and extends in afgenerally'opposing direction, said additional'arm beingprovided with a lateral notcllfat its extremities. .x V i l 7. Apparatus as claimed in el'aim'fl6. characterized .in ,that said impeller assenibly is provided witha hub cup just below sa'idllower impeller disc foriecei'ving. the par- 8.' An 'impeller yane for use in 'ing di o ea at anangmeriabeur 9,0

5 ized in that said inward portion of said arms is disposed at an angle of about 40 relative to the main radial portion, forming with said outward extremity a cupped barrier.

10. An impeller vane as claimed in claim 9 characterized in that said main radial portion is provided with bosses for receiving bolts for securing said vane to the impeller assembly.

11. An impeller vane as claimed in claim 10 characterized in that said vane includes an additional arm which extends from said main radial portion in a generally lateral direction opposed to that of said first-men- References Cited in the file of this patent UNITED STATES PATENTS 2,992,783 Wirth et a1. July 18, 1961 2,992,784 Behnke et al. July 18, 1961 3,058,679 Adams Oct. 16, 1962 3,083,921 Danyluke et al. Apr. 2, 1963 

1. IN A CENTRIFUGAL PULVERIZER FOR REDUCING THE SIZE OF PARTICLES OF MATERIAL, AND IMPELLER ASSEMBLY ADAPTED TO BE ROTATED AT HIGH SPEED, SAID IMPELLER ASSEMBLY INCLUDING AN UPPER AND A LOWER HORIZONTALLY-DISPOSED IMPELLER DISC, AND A PLURALITY OF RADIALLY-DISPOSED IMPELLER VANES VERTICALLY SECURED BETWEEN SAID DISC, EACH OF SAID IMPELLER VANES HAVING A RADIAL MAIN PORTION AND HAVING A PLURALITY OF CUPPED ARMS EXTENDING GENERALLY CIRCUMFERENTIALLY THEREFROM IN THE DIRECTION OF ROTATION OF SAID IMPELLER ASSEMBLY AND LOCATED AT DIFFERENT RADIAL DISTANCES FROM THE AXIS OF ROTATION, SAID CUPPED ARMS BEING CUPPED INWARDLY FORMING POCKETS, THE EXTREMITY OF EACH OF SAID ARMS HAVING A RELATIVELY LARGE LATERAL NOTCH DISPOSED BETWEEN THE UPPER AND LOWER DISCS FOR PASSAGE THERETHROUGH OF PARTICLES OF MATERIAL. 